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<head><meta charset="utf-8"><title>Settings for fast rebuilds when working on HIR/lowering? · t-compiler/help · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/index.html">t-compiler/help</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Settings.20for.20fast.20rebuilds.20when.20working.20on.20HIR.2Flowering.3F.html">Settings for fast rebuilds when working on HIR/lowering?</a></h3>

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<a name="182135157"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Settings%20for%20fast%20rebuilds%20when%20working%20on%20HIR/lowering%3F/near/182135157" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> osa1 <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Settings.20for.20fast.20rebuilds.20when.20working.20on.20HIR.2Flowering.3F.html#182135157">(Nov 28 2019 at 20:50)</a>:</h4>
<p>What is the fastest way to rebuild stage 1 compiler when working on <code>librustc/hir</code>? Currently adding a single <code>debug!</code> line takes 12m with <code>./x.py build --stage 1 -j 8</code>.</p>



<a name="182135270"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Settings%20for%20fast%20rebuilds%20when%20working%20on%20HIR/lowering%3F/near/182135270" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> osa1 <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Settings.20for.20fast.20rebuilds.20when.20working.20on.20HIR.2Flowering.3F.html#182135270">(Nov 28 2019 at 20:53)</a>:</h4>
<p>I think <code>--stage 1</code> rebuilds libraries too, which makes sense, but my changes won't be changing generated code so if possible I'd like to avoid that and only build the compiler. Is this possible?</p>



<a name="182136376"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Settings%20for%20fast%20rebuilds%20when%20working%20on%20HIR/lowering%3F/near/182136376" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Settings.20for.20fast.20rebuilds.20when.20working.20on.20HIR.2Flowering.3F.html#182136376">(Nov 28 2019 at 21:19)</a>:</h4>
<p>you can likely get away with <code>x.py build --stage 1 src/libtest</code></p>



<a name="182157031"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Settings%20for%20fast%20rebuilds%20when%20working%20on%20HIR/lowering%3F/near/182157031" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> osa1 <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Settings.20for.20fast.20rebuilds.20when.20working.20on.20HIR.2Flowering.3F.html#182157031">(Nov 29 2019 at 07:50)</a>:</h4>
<p>Just tired that, but it still rebuilds <code>std</code>.</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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